This invention pertains to the art of valves and more particularly to valves of the type commonly referred to as bellows valves. The invention is particularly applicable to an inverted bellows valve and will be described with particular reference thereto. However, it will be appreciated that the invention has broader applications and is adaptable to use in other environments and applications.
Increased use of bellows valves has been fostered by the need to seal the valve interior from the external environment as may, for example, be encountered in special handling of corrosive type fluids. The term inverted bellows refers to the fact that the bellows is sealed relative to the stem or stem tip such that the system fluid acts externally on the bellows, rather than internally. It has been found that the bellows in such valves can withstand greater external forces than internal forces, thus permitting use of inverted type bellows valves at higher system pressures. Many of the prior art devices have maximum pressure ratings of approximately 600 psi, and commonly assigned U.S. Pat. No. 4,201,366 has a pressure rating of 1000 psi maximum. Reliable shutoff operation under any condition of pressure or vacuum within its rating is also an important requirement along with decreased distortion of the bellows as it is cycled under pressure. Increased standards required for industrial utilization have not heretofore been met by the known prior art devices.
It has, therefore, been desirable to improve on the basic design whereby the valve structure would be capable of withstanding higher pressure applications without loss of quality in the valving assembly. The subject new design is deemed to meet these needs and others, and provide a new and improved inverted bellows capable of higher pressure ratings.